希瓦氏属细菌基因组中存在大量原噬菌体，对该属细菌原噬菌体的研究却鲜有报道。我们前期研究发现模式菌株MR-1的H-NS蛋白可抑制基因组上ssrA位点插入的原噬菌体CP4-57So的切离，随后我们发现W3-18-1的ssrA位点也存在一个原噬菌体ΦS73181，同一原噬菌体也存在于该属MR-7中，但并没有插入在ssrA位点。原噬菌体ΦS73181与CP4-57So的大小和内部基因组成差异显著。本项目研究目的在于探求H-NS对原噬菌体的调控究竟是依赖原噬菌体的种类与功能，还是依赖其在基因组中插入的位置。我们将诱导原噬菌体切离，采用基因缺失和回补等遗传操作手段、运用实时荧光定量PCR、EMSA等技术，检测ΦS73181在W3-18-1和MR-7中的功能以及宿主H-NS对ΦS73181切离的调控。研究将帮助我们进一步了解细菌与噬菌体相互作用的机制，并为细菌间水平基因转移的调控提供有价值的科学证据。

Through comparative genomic analyses we found that prophages are widely spread in the genomes of bacteria from Shewanella genus. However, the host regulation of these prophages remains largely unknown. Previously we found that host factor H-NS protein is involved in the regulation of prophage CP4-57So which is inserted at ssrA gene of Shewanella oneidensis MR-1 genome. Additionally, another prophage ΦS73181 was found at ssrA gene location in genome of Shewanella putrefaciens W3-18-1. Interestingly, the same prophage ΦS73181 was also found in Shewanella sp. MR-7 strain. However, ΦS73181 was not inserted at ssrA in genome of MR-7. The size and gene contents of prophage ΦS73181 were different from these of CP4-57So. The purpose of this study is to explore whether prophages are regulated by H-NS in other Shewanella bacteria, and to find out this regulation is dependent on the function of prophage or the location of the prophage inserted. Excision of prophage ΦS73181 will be induced from the genome of W3-18-1 and MR-7, respectively, and gene knock-out strategy as well as Real-time qPCR technology will be used to explore the regulation of H-NS on prophages. This project will help to understand the interaction between prophages and their bacteria host, as well as the regulation network of genes that are horizontally transferred among species.